class User:
    """一个用户类"""

    def __init__(self, first_name, last_name, age=None, description=None):
        self.first_name = first_name
        self.last_name = last_name
        self.age = age
        self.description = description

    def describe_user(self):
        print(f"{self.first_name} {self.last_name} has properties: age : {self.age}, description : {self.description}")

    def greet_user(self):
        print(f"Hello {self.first_name} {self.last_name}, Nice to meet you")


if __name__ == '__main__':
    bob = User("王", "大锤", 20, "暴力男")
    bob.describe_user()
    bob.greet_user()
